If you mean directly experience, that would be true, but clearly we do indirectly experience them and they are demonstrably real. I guess your point is to show the unreliability, indeed almost the unreality, of our experiences. Since they are central to the antecedent of Arthur's argument, you're saying drawing conclusions about what must be real would be a mistake.
No, my point was just the opposite. Considering that trying to observe phenomena at the atomic or sub-atomic level affects what is being observed, there is much unreliability and "unreality". How do we know what is actually happening when we aren't "observing" what is happening? We know far less about reality at the atomic or sub-atomic level than we do at the level which we experience things (directly).